A wireless air interface of a UMTS (Universal Mobile Telecommunications System, universal mobile telecommunications system) uses a WCDMA (Wideband Code Division Multiple Access, wideband code division multiple access) technology.
Currently, it is allowed in many countries to deploy WCDMA at a main frequency band 900 MHz of a GSM (Global System for Mobile Communications, global system for mobile communications), to introduce the WCDMA into a new region by using a few base station sites, so as to bring a better coverage effect. Coordinative deployment is a specific implementation mode of deploying the WCDMA and the GSM at a same frequency band. The coordinative deployment means that the WCDMA and the GSM share a same site, and are deployed by a same operator. A carrier interval between the WCDMA and the GSM is compressed into be smaller than 2.8 MHz. Although the coordinative deployment saves spectrum resources, because the carrier interval between the WCDMA and the GSM is small, inter-system interference is large, which causes network communication performance to deteriorate. To solve the problem, a narrow bandwidth technology applied at a network side is proposed.
The narrow bandwidth technology aims at reducing a passband bandwidth and/or increase a transition band suppression characteristic. By using the narrow bandwidth technology at the network side, a bandwidth occupied by a transmission signal is reduced, so that in the coordinative deployment, the inter-system interference is reduced. By taking an example that the narrow bandwidth technology is used by a communication device supporting a WCDMA network, filtering waveforms of a filter of the communication device are as shown in FIG. 1, where a waveform 1 is a bandwidth waveform specified in an existing communication standard; a waveform 2 is a bandwidth waveform in a first narrow bandwidth mode, and in the first narrow bandwidth mode, the passband bandwidth is the same as the passband bandwidth specified in the existing communication standard, but the transition band suppression characteristic is increased; and a waveform 3 is a bandwidth waveform in a second narrow bandwidth mode, and in the second narrow bandwidth mode, the passband bandwidth is reduced, and the transition band suppression characteristic is increased. In the narrow bandwidth mode, the width of the passband bandwidth and a value of a transition band suppression characteristic parameter may be specifically set by an operator according to actual demands. As an example instead of a limitation, as shown in FIG. 2, during the coordinative deployment of the WCDMA and the GSM, if the communication device of the WCDMA network uses the narrow bandwidth technology, a 4.2 MHz narrow bandwidth is supported in a 5 MHz WCDMA frequency band, and a 0.8 MHz bandwidth may be saved, which is used by a GSM network; a 3.8 MHz narrow bandwidth is supported in the 5 MHz WCDMA frequency band, and a 1.2 MHz bandwidth may be saved, which is used by the GSM network.
In the process of implementing the present invention, the inventor finds that the prior art at least has the following problems:
In the existing WCDMA communication standard, a terminal side does not support the narrow bandwidth technology. When the network side applies the narrow bandwidth technology, because the terminal side does not support the narrow bandwidth technology, intra-system performance loss is caused by mismatching between a receiving bandwidth and a transmitting bandwidth, and interference between adjacent systems is increased.